1. Field of the Invention
Aspects of the present invention relate to an organic light emitting display apparatus and a method of manufacturing the organic light emitting display apparatus. More particularly, aspects of the present invention relate to an organic light emitting display apparatus in which a manufacturing process is simplified and costs for the manufacturing process are reduced and a method of manufacturing the organic light emitting display apparatus.
2. Description of the Related Art
Organic light emitting display apparatuses are self-emitting display devices having an organic light emitting layer between a pixel electrode and an opposite electrode. In such organic light emitting display apparatuses, an anode voltage and a cathode voltage are respectively applied to the pixel electrode and the opposite electrode, and thus holes injected from the pixel electrode are transported to a light emitting layer through a hole transport layer and electrons injected from the opposite electrode are transported to the light emitting layer through an electron transport layer. The transported holes and electrons recombine to generate excitons, and the excitons transfer energy to fluorescent molecules of the light emitting layer while the excitons transition from the excited state to the ground state. Then, the fluorescent molecules emit light to form an image. Organic light emitting display apparatuses are classified into active matrix (AM) types and passive matrix (PM) types. An AM type organic light emitting display apparatus capable of displaying a high quality image has been widely employed.
FIG. 1 shows a schematic cross-sectional view of a conventional AM type organic light emitting display apparatus. Referring to FIG. 1, a conventional organic light emitting display apparatus includes a substrate 10, a buffer layer 11, a semiconductor layer 21, a gate insulating layer 12, a gate electrode 22, an interlevel dielectric layer 13, source and drain electrodes 23 and 24 (the semiconductor layer 21, gate electrode 22, and source and drain electrodes 23 and 24 forming a thin film transistor), a planarization layer 14, a pixel defining layer 15, a spacer 16, a pixel electrode 26, an organic light emitting layer 27 and an opposite electrode 28. The planarization layer 14 is formed to cover the thin film transistor, and a via hole 25, which exposes the drain electrode 24 of the thin film transistor, is formed through the planarization layer 14. A pixel electrode 26 is deposited and patterned on the planarization layer 14 to contact the drain electrode 24 through the via hole 25.
When the pixel electrode 26 is patterned, the pixel defining layer 15, which defines light emitting regions, and the spacer 16, which protects the organic light emitting layer 27, are deposited on the planarization layer 14, and the pixel defining layer 15 and the spacer 16 are patterned to expose the pixel electrode 26.
However, since two masks are used to pattern the pixel defining layer 15 and the spacer 16 in a conventional organic light emitting display apparatus, the manufacturing process is complicated, and thus the costs for the manufacturing process are high. Alternatively, the use of a half-tone mask including a semi-penetrating unit in addition to a light blocking unit and a light penetrating unit may simplify the manufacturing process, but this technique may also lead to high costs for the manufacturing process even though only one mask is used, since a half-tone mask is more expensive than a conventional mask.